L UST
by Lur27
Summary: Love and Unresolved Sexual Tension make a very dangerous combination. Series of one-shots. Reader's collaboration will be appreciated.
1. Chapter 1

**IMPORTANT! Note for readers:** I'm planning this story as something interactive between you and me. It's going to go on until you guys want to, and that means I'm going to need your ideas and cooperation to make this work. These stories I plan on writing are going to be based on Castle's and Beckett's UST, which means they won't be actually _doing_ anything. Let's call them vivid fantasies/situations that we're going to 'witness' while reading (or writing, in my case).

So, what I'm asking here is for your help. Feel free to suggest, point or ask for whatever crosses your mind and I'll write something about those ideas you give me.

Have in mind that I'm only one person and it'll take time for me to go over all your suggestions, so please, be patient with me! I'm writing another multi-chapter story and I'll have to divide my time.

I'll be willingly waiting for your great ideas so I can go on with chapter 2! Thank you! :)

**DISCLAIMER: No, not mine… :( At least I get to play with them ;)**

* * *

**CHAPTER 1: You Give Me Fever.**

They had been working for four hours straight on the murder board, all of them adding pictures, descriptions, new leads, CSU and autopsy reports, persons of interest and whatever they could hang or write in there that could help them catch the bad guy.

They were all a little shocked because the victim was a very young girl, and even though any of them said anything, that fact made them more committed to the investigation.

It was already well past 10 pm when Beckett sent the boys home. Castle denied leaving until she did, and Kate was kind of thankful for that. She had grown accustomed to his company at the precinct and being there by her own felt a little awkward lately.

Castle excused himself to make a visit to the restrooms and Kate went to the break room to make both of them some coffee.

Public domain was that Beckett was not good friends with the Espresso machine, and to be truthful to that saying, right when she was about to heat the milk, the traitorous appliance started to expel steam in every direction burning her hand. Her thumb was the most damaged part of it and she tried to sooth it putting it in her mouth.

Castle, who was already at the break room's door watching her, could not keep his mind out of the gutter, going a million miles away, imagining what would happen if he was not such a chicken and made a move on Beckett. That simple gesture of her sucking on her thumb had made him go wild.

xxxxxxxxxxxx

_Rick walked towards the detective, his gaze fixated on her luscious lips, while they sucked her burnt finger delicately. She was oblivious to his presence and startled a bit when she felt his hand on her shoulder._

"_Can I help?" He asked, his voice sounding deep and seductive._

_Kate gave him a shy smile and pulled her thumb out of her mouth, her saliva shining on it and making it cool under the room's air. "Can you heal it?" she asked, her eyes daring him._

_Rick took her hand in his and moved it to his mouth, circling the little pad with his own lips and lapping it with his tongue. Kate let out a soft, surprised moan that got under his skin making him so very hot. That woman was going to be the death of him._

xxxxxxxxxxxx

"Castle, are you ok?" Beckett asked waving her hand in front of Castle's eyes and giving him a concerned look.

"Uh?" He blinked out of his fantasy, kind of confused. "Yeah, fine." God, how did he want her.

"You were in another planet…" The cop added with a soft laugh. "Here, I made you coffee." She said with a wide smile. "Take it as a once in a life time treat; I almost lost my hand in the attempt."

Castle managed to let out a silly laugh before taking the cup from her hand, brushing their fingers together. Just that little contact triggered another 'trip' to his private world.

xxxxxxxxxxxx

_Pulling her finger out of his mouth he kissed her palm before drawing her closer to him so he could speak in her ear._

"_Anything else you got burned?" He asked mischievously, his eyes not leaving hers._

_Kate replied with a smirk of her own, nodding her head and brushing her index finger over his lips. He opened his mouth and licked the slender digit with the same intensity he did the first one, letting his teeth graze her tender skin and making her shiver._

_Rick let out a loud groan, letting go of her hand and reaching for her mouth instead. He kissed her passionately, his tongue wrestling hers for every molecule of oxygen that was left in their mouths. Her teeth bit on his lower lip, making him moan and he returned the 'favor' by pulling on her hair lightly._

"_God, Castle! This feels so much better than I thought it would." She said on a gasp, running her fingers through his skull._

xxxxxxxxxxxx

Castle let out soft moan without even realizing it, he was totally oblivious to the 'real world' by then, and he didn't noticed Beckett's concerned face when she turned around and found him still at the break room's door, staring blankly at nothing in particular, with his coffee in hand and his face completely flushed.

She walked towards him putting a hand to his forehead. "Castle, are you sure you're ok?"

The writer jumped at the contact with her hand and had to reach for the door's frame to steady himself. "Yeah, fine. Why?"

Beckett narrowed her eyes giving him one of her best 'looks' and shook her head. "You're acting weird. You're all flushed, I'm worried you might be running a fever."

Castle managed to hold a little chuckle. _If you only knew,_ he thought. "Why, detective? You worried about me? I'm touched." He joked.

Kate moved closer to him holding his head with both her hands, making him lean it downwards so she could press her mouth to his forehead. When he felt her soft lips pressed against his flesh, he jumped, moving himself from her touch. Not that he was complaining…

"What are you doing?" He asked; the air caught up in his lungs.

The detective gave him a mischievous smile and took a step closer. "I'm just checking your temperature, Castle. Relax."

He was starting to feel _really_ hot, and not the way Beckett thought. He couldn't let her get any closer or he'll end up embarrassing himself. "Don't you have to use a thermometer for that?"

Kate narrowed her eyes and smirked. "Ok. I think I have one somewhere in my desk." She said. "But first, let's get you to the couch so you can lay down, ok? You don't look good."

Castle frowned. Worried Beckett was kind of cool. She was touchy and caring and she didn't mind staying close to him, but he couldn't deal with that right now.

He was still thinking about how to make her stay away, when he felt her hand in his shoulder, pushing him towards the couch. He startled, taking a step forwards and tripping over Kate's foot, falling over her. It was a good thing that the doorframe held her stopping the fall. But then again, maybe it was not that good. His whole body was pressed against hers and he was absolutely sure that she could _feel_ the consequences of his dirty mind. Busted.

None of them moved for a while. She was surprised and worried about him and he… Well, he was just embarrassed.

"Hey. You ok?" Beckett asked after a couple of minutes.

Castle nodded, his nose buried in her neck, her scent creating new images in his mind that he really needed to control. "I'm fine."

At last she pushed him gently and held his arm to help him walk to the couch. When he was sat and comfortable – she made sure of it – she went to look for the thermometer, coming back with it in no time.

"Here it is." She said leaning over him. "Let me undo a couple of buttons so I can put it on." She added, her hands already working on his shirt.

The touch of her hand on his bare skin when she put the thermometer under his arm made him shiver. Kate felt it and her face softened, giving him a warm look and brushing his hair out of his face.

This really was a discovery. He needed to get sick more often. Actually, he needed to get sick _for real_ more often.

They waited there, sat side by side until the little thing beeped, letting them know that his charade was coming to an end. Kate reached for it and checked the answer.

"Hmm. 100.4, Castle. You need to go home." She said, almost sadly. "You need rest and some Tylenol."

Rick couldn't hide his surprise. He was sick? Could a steamy fantasy give you a real fever? Or was it the fever making him imagine those things?

He stood up and followed her to the bullpen. "But you still have things to do and I don't want to leave you alone." He whined.

Beckett laughed and rolled her eyes. "I'll be fine, Castle. You need to go to bed and get rid of that fever. I need my whole team working on this case, ok? Go home."

He took his phone out and called a car. At least that gave him more time with her that just leaving and hailing a cab. She kept touching him every few minutes with the excuse of checking his temperature and, even though he felt perfectly fine, he kept looking at her with puppy dog eyes.

The car arrived and he got a text from the driver. "Albert is here." He said, standing from his chair and putting on his coat. "See you tomorrow, Beckett. And thanks for… taking care of me."

Kate just smiled and shook here head. "No need to thank me." She said softly, her eyes locking with his. "Night, Castle. Get well."

* * *

He arrived home twenty minutes later, and before taking the Tylenol; he decided to put on the thermometer to see if there had been any changes. He waited a couple of minutes until the little device beeped, and then took it out to read it. 97.2 Perfectly normal. Now, _that_ was weird.

He fished for his phone and sent her a text:

_I just took my temperature and it's absolutely normal. Anything you want to tell me, detective?_

He didn't have to wait long for her answer:

_Normal, huh? Maybe it's me who gives you fever, Writerboy? ;)_

He smiled, putting his phone back in his pocket. There was no need to reply to that, she already knew the answer.

* * *

**Thoughts? Ideas for next chapter? Want to kill me because you hate it? Let me know ;)**


	2. Chapter 2

**A/N:** Chapter 2! Yay! I'm sorry it took so long :( This one was born form **droarke**'s (with a dot after the d) idea. He/She (Sorry, I don't know your gender...) suggested that we always get to see how Kate affects Castle, but we never get to see how Castle affects Beckett. We never get to see him seducing her, even though he's supposed to be a womanizer. Well, this is my attempt to show this. I have to say that I'm not very happy with it. I've been struggling for days, writing, rewriting and writing again and this is the best I could do. I'll understand if you hate it...

Anyway, thanks to all of you for reading, reviewing and adding this to alerts and favs. It really means a lot to me :) You guys are really the best.

I hope you enjoy the story, and remember I'm open to suggestions for new chapters. You can leave a review or PM me with your ideas. I'll be happy to make them come true :)

This is not beta-ed so excuse my grammar and all that stuff. I really try! If you find anything I need to correct, please let me know. Thanks!

* * *

**Chapter 2. I'm Immune To Your Charms.**

Making Alison Neal confess the murder of her ex-boyfriend was being absolutely impossible. Beckett tried everything; from tricking her into thinking they had the murder weapon, to make her believe there was a witness who was willing to talk. Nothing worked. They had no tangible proof of her crime, but they were 100% sure that she was the killer.

After three exhausting hours of interrogation, Esposito and Beckett walked out of the room, both sporting faces of defeat. Castle, who had been watching their efforts from the observation room, asked if he could talk to the suspect for a moment.

"Knock yourself out, bro. There's nothing we can do right now…" Espo said, throwing the folder full of evidence over the table under the two-sided mirror.

Beckett stopped the writer before he could get out of the room. "Why do you want to talk to her, Castle?"

"Pure curiosity, detective. She might be the first person I know to commit the perfect murder." He replied with a wide, excited smile on his face.

The detective let go of Castle, shaking her head and mumbling something to her colleagues, who where already laughing and making jokes about him.

Ten minutes later, and after one of Castle's seduction and story telling demonstrations, Alison was confessing her crime to a very self-conceited writer.

* * *

At night, while the four of them were sharing a drink at the Old Haunt, celebrating having closed the case, Beckett was still amazed and annoyed at how Castle had made the suspect talk.

"I can't believe she fell for that, Castle." Kate repeated for the thousandth time. "Seriously."

The writer let out a silly laugh before taking a long sip of his drink. "It's a gift, Beckett. I'm _that _good." He said smugly. "Women can't resist me or my many charms"

A loud snort came out of the detective's mouth. "Gosh, Castle. You're so modest!"

"Hey! I can't deny the obvious." He replied. "I'm telling you, Beckett. I can make any woman melt, if I want to. I didn't get my reputation for nothing."

Kate was playing with her straw, moving it in circles inside the tall glass. At last, she took a long sip and shook her head. "Sure, Castle. Whatever you say."

"I'm deadly serious, detective." He said, meeting her eyes. "Any woman."

Beckett let out a laugh and raised her brows. "Not me, Writerboy! I'm immune to you _and_ your charms." She shot, getting up from her stool and walking towards the boys, who were playing a game of darts not far from them. _You're such a big, fat liar, Kate Beckett._ She thought as she approached the dartboard.

Castle stayed where he was, hiding a mischievous smile with his glass. "Ok, you've asked for it, detective. We'll see how immune you really are."

* * *

Richard Castle was a man on a mission that slow Thursday morning, and his muse was completely unaware of it, which was perfect. He had waited a couple of days to put his plan into practice, taking the time to think about how to _'melt'_ Detective Beckett.

When he arrived at the precinct he found Beckett at her desk working on her paperwork, her brows furrowed in concentration in that way that made her look so cute. When he reached his chair, he sat down and handed her a cup of coffee and a big, sugary and delicious bear claw. The detective frowned a little when she saw the pastry, he only brought her one when he thought she needed to cheer up, like after tough cases or one of their frequent, little fights. Either way, she just took it, smiled and went back to her job.

As his strategy to catch her attention, Castle tried to remain as silent as he could while she worked, and even helped, taking for himself a small stack of folders. After an hour of work and unusual silence, Beckett spoke.

"Castle, are you ok?" She asked concerned.

The writer gave her an amused look. "Yes. I'm absolutely fine. Why do you ask?"

"You're quiet." She said, narrowing her eyes and trying to find a flaw in his poker face.

"So? I thought you wanted me to be quiet when you were working."

"And yet you never do what I say. What's changed today?" She asked, her tone becoming more and more urgent with every word.

Castle shrugged. "I'm concentrated." And went back to his report.

Beckett quirked an eyebrow and stared at him for a couple of minutes until she gave up and returned to her paperwork. He was cute when he was concentrated.

* * *

A couple of hours went by before Castle left his comfortable chair to go make them both some coffee. When he was coming out the door of the break room he saw her rubbing her neck, moving her head from side to side, trying to ease the rigid muscles.

He walked towards her, put the two cups on her desk, right beside her computer monitor, and then removed her hands from her neck, replacing them with his.

Kate froze. Her eyes went wide, her breathing stopped and the muscles that felt stiff already, were now rock hard.

After a few seconds he started moving his hands, rubbing the muscles in her shoulders. Then his skilled digits moved upwards, reaching the soft, bare skin of her neck, making her shiver and covering her in treacherous goosebumps.

_Oh my God! What is he doing? He shouldn't be doing this… Oh, God, but it feels so good… _Her mind was racing. _You need to stop this, Kate. Now!_

Castle felt her getting more rigid with every stroke, so he leaned down, his mouth to her ear, the air that came out of his nose with every breath brushing the silky skin of her jaw and neck.

"You need to relax, Beckett. I'm rubbing your neck, not biting it!"

She could feel the smile around his words, his nose gracing the case of her ear as he retreated back to his previous position.

_Hmmm. Biting. Yeah, that would be nice…_ She thought, letting out an uncontrolled little moan when he found a particularly tender spot. _Damn it, Kate! Stop this. Stop this RIGHT NOW!_

Castle smirked at the muffled sound that came out of her mouth. He'd be more than happy to make her moan again, in a very different way, in a very different situation.

Beckett lifted her gaze from her paper in a superhuman effort, finding Ryan and Esposito looking back at her with matching, stupid grins on their faces.

_Oh Shit! That's right. People, Kate. There are people here. You're at work and he shouldn't be touching you like that. Actually, he shouldn't be touching you at all._

Taking a deep breath and shutting her eyes hard, the detective shrugged off Castle's hands from her neck, letting them fall to her back. Then she turned her head to look at him, smiling apologetically, as she gave a quick nod towards the boys to let him know what was going on.

Castle winked at her -_He winked at her! –_ Moved his hands off of her back, took his black 'Richard Castle' mug from her desk and sat on his chair, going back to his job with a smug grin on his face.

Kate stared at him for a long time through narrowed eyes, trying to understand his strange behavior. _What the hell was that, Castle?_

* * *

By noon, the awkwardness between them had practically disappeared, and she accepted willingly when he offered to buy her lunch.

They left the precinct side by side, talking about the amount of work they had accomplished that morning, and how great would it be if they managed to finish all their paperwork before they had to leave that evening.

They arrived at Remy's and claimed their regular booth after greeting Becky, their waitress. She already knew their regular choices, so she just asked them what they wanted to drink and left.

"I'm starving!" Castle said, after a minute or two of uncomfortable silence. Maybe the awkwardness was not gone at all.

Kate looked up from studying her hands and nodded. "Yeah, me too."

He was feeling kind of bold after the massage at the precinct, and reached for her hand. "Hey, you ok?"

"Yes. Just a little… I don't know." She took a deep breath and met his eyes again. "Castle, what was that before? The rubbing my neck thing…" _And when will you do it again? - NO Kate! Stop it!_

He could tell she was uneasy, but she didn't pull her hand from his. That had to be good, right? "You seemed to be in pain and I wanted to help. Is that bad?"

Her eyes were now staring at their joined hands, and he could see a soft smile curling up her lips. "No. Not bad. Just… weird." _ Yeah, so weird it made me think about some inadequate stuff involving you, me and a lot of biting._

Castle could see her face blushing and her eyes blinking rapidly, as if she were trying to push something out of her mind. "I don't understand why does it have to feel weird. I mean, we're friends, right?" He asked, his thumb stroking her knuckles lazily.

"Yes. Of course we are." She agreed. _And for the shake of that friendship you should stop doing _that _to my hand…_

"Don't you think people give too much importance to physical contact?" His eyes were focused only in her and she felt the heat swallowing her from the inside out. "I mean, it's important, and definitely pleasurable, but sometimes it's like you can only touch someone if you're actually sleeping with them. Ain't that stupid?"

Beckett could only nod her head. She was too busy trying to swallow the big lump in her throat, too distracted by the feeling of his hand in hers and too hypnotized by the sound of his voice to articulate a sound response.

"You see Beckett, we ourselves practically never touch each other, and we've been friends for what? Three years? I have newest friends I greet with a kiss every time we see each other, but with you… We're always at an arm's length distance and I don't like it. We should touch more."

Kate's brain decided to come back to life right then, but it only registered the last four words of his speech. "We what?" She asked, completely lost.

Castle's hand stopped it's stroking and squeezed. "We should touch more, Beckett."

_Oh, yes. We certainly should. Gosh, I wish I could tell you how and where I want you to touch me right now. – For God's shake, Kate! He's not talking about that. Because he's not, is he? _"We should touch more? How?" She asked as nonchalantly as she could manage.

The writer raised their joined hands to show her. "Like this. I like holding your hand just because I want to. It doesn't have to mean anything, right?"

"Uh huh." She replied. _Yeah, like we could now walk into the bullpen holding hands and it wouldn't mean anything. _

"Although, sometimes, just holding hands can mean everything. Sometimes." He added, sort of absentmindedly.

That caught Kate's attention and made the little bungee-jumper in her belly launch himself into space. _Maybe he _was_ talking about that after all._

* * *

They ate mostly in silence; Castle's hand reaching for hers the moment it touched the table. He kept feeding her French fries from the basket they always ordered to share, and she kept blushing every time her lips touched the skin of his fingers.

By they time they paid and stood up to leave, detective Beckett was so turned on, she didn't know what to do with herself.

She took her coat and put her arms through the sleeves easily, but when she pulled the collar to straighten it, her hair got tangled to the first button, making her gasp in pain. Castle noticed and came to the rescue.

"Here. Let me." He said from behind her.

He leaned into her, his left hand resting at her waist while the right tried to untangle the rebel lock from her button. He was _so_ close Kate could feel every breath he took, the air coming out of his nose brushing her skin every few seconds.

After untangling the mess of hair and plastic he moved to get off her, his nose brushing her jaw and making her squirm. When he felt it, he leaned closer to her again and nuzzled her ear before he said "Gotcha!"

She was too lost on the sensations and only could reply with a "Huh?"

Then, Castle grabbed her hair, pulling it to the other side so he could talk on her ear without any barrier. "I got you, detective." He laughed. "Either I'm better than you thought, or you're not immune to me at all."

Before she was able to process his words he was out the door of the restaurant, leaving her planted there like a statue, trying to find out the right words. Right then, she could only think one thing: _Richard Castle, you are SO dead!_

* * *

_**Ok, you guys can kill me now... Just be gentle, please! :P**  
_


	3. Chapter 3

**A/N:** Hello! Ok, guys, four things: First of all, I'm really sorry it took me SO long to update this. After Always I wasn't sure if I wanted to go on with this series, but this idea came to my mind and I wanted to write it. Let me know if you want me to keep going with this, ok? Thanks! :)

The second thing is that, during most of this story, Beckett is talking to Castle through a microphone from a stakeout van and I put her lines in italic so it's easier for you to follow. Let me know if it didn't work.

Third, this is not beta-ed so please, excuse my horrible grammar mistakes. I'm trying, really.

And fourth, thanks to CastleWriter16 for putting up with me and giving me few lines to go on with this. You rock, girl!

ENJOY! :)

**Chapter 3. Undercover Desire.**

Detective Kate Beckett was looking intently at the tiny monitor in front of her, trying to school her facial expression, so her worry about her partner didn't show too much. Her boys were flanking her sides, one setting the sound equipment while the other mumbled something into the microphone placed on the narrow counter of the stakeout van.

She still didn't know how this had happened, but somehow, Castle had managed to put himself in the first line of fire, volunteering for an undercover mission. The weirdest thing of it all had been that Gates had agreed on letting him do it; Kate didn't know if it was because she thought it was a good idea, or because she thought it was a good way to get rid of him forever. If those guys found out who he was, Castle could consider himself dead.

Their target was Linda McKenna, the suspect's daughter. She was in her thirties and her long dark hair, blue eyes and sensual curves were her cover letter and Beckett's biggest concern.

Castle's job was making contact with the woman, talk to her and maybe even seduce her, so she would give out some information about the murder of one of her father's closest men. All their evidence pointed to Mr. McKenna, a businessman somehow related to Irish mafia, but all they had was circumstantial, and as it was practically impossible getting close to the old man, they had decided that his daughter would be a better option.

That's when Castle had jumped in saying he was their best asset for that mission. She had laughed at him, but it had turned out that everybody seemed to think he was right, and she had been the only one left trying to talk Rick out of it. No need to say that she had failed miserably.

* * *

Castle was inside the Four Seasons hotel, where one of New Your City tycoons was celebrating his fifth anniversary with his almost thirty-five years younger wife. It had been a luck they had managed to put Castle on the guest list.

As he was scanning the room to see if he could find Linda, the writer kept talking to the team through the tiny mic he was wearing in one of his shirt buttons.

"Oh, guys, you should see this. It's amazing."

Esposito let out a snort. "We _are _seeing it, Caste. You're wearing a cam, remember?"

"Oh, yeah. That's right. I keep forgetting I'm a wired mole."

"_How is that when you can't stop talking to us?"_ Beckett scolded him. _"Will you please focus and find that woman before we get old? This is taking forever…"_

Castle smirked as he took the glass of Champaign a waiter was offering him. "Relax, Beckett. It's a party."

The detective rolled her eyes and turned her attention to the screen before her, where she spotted Linda talking to a group of people about 20 feet away from Castle.

"_Ok, Castle, one o'clock, red dress. Be smooth."_ Beckett spoke into the mic.

Castle let out a laugh and put his glass on a tall cocktail table. "I'm always smooth, detective."

"_P-lease, Castle. It's me you're talking to. You're as smooth as a blow to the head. Now go talk to her so we can go home, will you?"_ She commanded. _"Be careful."_

"Is that concern I detect in your voice?" The writer asked, his grin showing in his voice.

Beckett sighed and shook her head. _"Just move and don't blow this!"_

* * *

Castle had made contact with their target almost an hour ago, and they still had nothing. Well, at least nothing relevant to the case.

Beckett was getting anxious, and her stomach was starting to churn at the view of her partner dancing and flirting with another woman.

He was being his charming self, offering Linda glasses of Champaign, making little jokes and talking in her ear as they danced too close to each other for Beckett's liking.

"You are certainly the most beautiful woman in the room." Castle told her. "I can feel the other men's eyes pointed at me, all of them wondering why am I so lucky." He stopped and looked into Linda's eyes for effect. "To be honest, I'm wondering that too."

"_Come on, Castle. Stop trying to score and make her talk about her father." _Kate said, invading his head for a few seconds. It was making her sick listening to him tell those things to a complete stranger.

After excusing himself with the woman, telling her he was going to get them something to drink, Rick walked to the bar so he could talk to the team without her noticing.

"Relax, detective! I can't just ask her about her father out of the blue. We just met." Castle mumbled as he approached the bar.

"_Oh, really. You can sign the chest of a woman you've met ten seconds ago, but you can't ask one that you've been talking to for an hour about something the whole city has seen on the news?"_

The writer asked for two whiskeys to the barman and then turned around so the man couldn't see him talking alone. "That's absolutely different. I need to get Linda ready."

"_For what, Castle? You want to take the prize home after the party?"_ Beckett shot, her jealousy threatening to show.

"No, but I need her to be a little more…easily persuaded." He walked away from the bar and back over to Linda, handing her the drink with a flourish. "Let's find somewhere a bit more private," he said, leading her to the sitting area.

_"Castle, focus!"_

"I am focused," he mumbled under his breath.

Linda stopped mid-step. "What was that?"

"You're beautiful," Castle murmured. "Let's sit down."

Much to his relief, Linda didn't suspect anything and sank into the leather couch. "So Rick. Tell me about yourself."

He heard Beckett struggling to hold back a laugh and rolled his eyes. "Well, I'm with the most beautiful woman I've ever met," he said slowly, sitting down next to her. "I love the color red," he mused, fingering the hem of her dress. "And I'm single."

_"Oh, for heaven's sake!"_

"Single, huh?" Linda smiled and knocked back her drink. "Not anymore."

"_Ha! You cannot be serious!"_

Ryan and Esposito shared an amused look at Beckett's reaction. They knew pretty well what was going on.

Meanwhile, inside the hotel, Castle was trying to avoid Linda's lips by smelling her neck and telling her he loved her perfume.

"It's delicious, and kind of sweet; just like you." He told her, his best smile curling his lips.

Linda giggled, covering her mouth with her hand. "You mean sweet or delicious?"

"_Seriously?"_

"Both, of course." He conceded. "Always both."

"_Ugh, you're hideous…"_

Suddenly, Linda's phone started ringing and she excused herself for a moment, walking to the other side of the room for more privacy.

Beckett took the chance to call her man (strategically speaking) into order. _"Castle, will you please stop the shameless flirting and go straight to the point? I wouldn't like to be still watching when you take her to bed."_

"Oh, come on, Beckett! You know I wouldn't leave you watching. I like it when you participate."

"_Castle."_ She warned him. _"Just let's get this over with, ok? Thank you."_

"But-"

"_Shush! She's coming back!"_

The brunette took her seat beside the writer, placing her hand high on his thigh and squeezing. "So, where were we, darling?"

Castle swallowed hard and took a deep breath. "Um. We were talking about perfume?"

"Oh, yeah. Sweet and delicious, right?" Her hand moved a little bit upwards, making Castle squirm.

"Uh huh." He replied on a breath.

"_What's she doing? Where's her hand? Castle? Where's her freaking hand?"_

In that exact moment a man entered the room with a gun in his hand, and walked directly towards Wilhelm McKenna; the businessman took out his own gun and shot the intruder without the blink of an eye in front of two hundred people.

Linda ran to her father the moment she heard the gunshot, leaving Castle in the couch from where the camera he was wearing had recorded the whole scene.

"_Castle, get out of there. NOW!"_

* * *

They were back at the precinct after having arrested McKenna for the murder of Patrick O'Neill, the man that had stormed the party. Now that they had his gun, they could compare it to the casings they had found at the first crime scene.

At least, there was a good side. In the case they weren't able to frame him for the first murder, they had two hundred witnesses and a videotape to prove the second one. McKenna was going to rot in jail.

Beckett stood up from her desk to dismiss the boys until next day followed by Castle, who rushed to help her put her coat on.

"Let me." He said, taking the garment from her hands. Then, taking advantage of his position, he leaned closer to talk in her ear. "You know, detective, as much fun as I've had tonight, it would have been a thousand times better if it had been you at that party with me, instead of Linda. She was the prettiest woman in the room, but just because you weren't there." He felt her shiver, put a soft kiss in her neck and went on. "I've spent the whole night wishing it was you who I was trying to seduce. I'd really like to _show _youhow hideous I can get to be."

With that, he turned around and walked to the elevator, where he pushed the button and waited for her to come back to earth.

For a couple of minutes Beckett remained glued in the same spot Castle had left her, her mouth hanging open and her pulse racing. When her brain started getting back enough blood to function, she grabbed her bag and joined her partner, who was already keeping the lift doors open for her.

The ride to the lobby was silent and Beckett's lower lip was suffering a severe attack, letting Castle know she was either nervous or confused; or maybe both.

The soft ding that sounded when they reached their destination made them both catch their breaths again. Beckett released her lip, and before Castle could step out of the metal box, she moved herself in front of him, putting a hand to his chest to stop him.

When his eyes met hers she smiled, leaned in closer to his ear and whispered, "You know, maybe you should stop wishing and start acting, Castle. Juts a little piece of advice."

Not needing to look at him to know the expression that was drawn in his face, she turned around and walked out of the elevator, waggling her hips and waving goodbye with one hand as she got out of the precinct, knowing it wouldn't take long until he would follow.

* * *

**So, that's it. Thoughts, please?**

**A/N: If you want me to go on with this series, please feel free to send me your ideas, new scenarios, whatever you may like to see happening here. Have in mind this is all about the UST! Thanks for your collaboration :)  
**


	4. Chapter 4

**A/N:** Hi there strangers! I'm sorry I had you waiting for so long. I've promised a million times that it wouldn't take me so long the next time, but I keep braking my promises, so I've decided that I'm not going to promise anything anymore. No expectations, no disappointment. This applies to those of you who are also reading 'An Unexpected Little Surprise'. I'm really sorry.

I'm on vacation at my mom's and I'll be staying here until July 23rd. That means that everything will come back to normal by July 24th or so, and I'll try to update on my regular basis again. Yay!

That said, I want to thank all of you for reading, reviewing, following and 'favoriting' this series. I'm having a lot of fun doing this. Please, keep submitting your ideas so I can keep this going.

Thanks to my beta, the amazing CastleWriter16 for giving me the idea of writing about Sorenson, and for editing this chapter for me. Love ya, twin ;)

Enjoy!

* * *

**Chapter 4: _Choose me or choose no one._**

The moment Gates told them that their team was required to collaborate with the FBI they all whined like little kids, but Castle was the one who almost threw a temper tantrum when they found out the lead investigator was no other than Special Agent Will Sorenson.

Just what he needed.

Now that he and Beckett had started to get closer, her ex-boyfriend had to make an appearance. Classic. What was it with him and timing when it came to that woman?

* * *

Special Agent Sorenson debriefed them on the case in the conference room. They were investigating the kidnapping of a 7-year-old boy. The main suspect was a former employee of the kid's father, who was taking revenge after being fired from his job.

After filling them in and giving them all the details they needed to know, Sorenson dismissed them so they could go back to the investigation. Beckett took the chance to go refill her cup of coffee and the agent followed her into the break room. Castle, who was following the guy's every movement around Kate, followed them and stood hidden right outside the door, trying to listen to their conversation.

"Still a coffee junky, huh?" The man joked, getting closer to Beckett.

She smiled and nodded. "As if that could ever change." She said, stirring the delicious beverage. "It's nice to see you again, Will; even under these circumstances."

Will smiled broadly, stepping a little closer to her. "Yes. It's nice to see you too." He replied, leaning on the counter. "I don't know how you do it, but you look even better each time we meet." He said, trying to act coy.

Kate laughed. "Don't go there, Will…" She warned with an amused tone.

"Oh, well, I can't help it. You're a very attractive woman, Kate. Ignoring that is practically impossible."

The detective blushed a little and tried to hide it, moving to put away the stirrer. She waited a second to compose herself and turned to face him again, getting a little closer to him so that she didn't need to speak out loud.

"Look, Will, I can't-" She stopped abruptly when she saw Castle walking through the door, looking a little bit disgusted. Just by the look on his face she could tell he had been eavesdropping. "Hey, Castle."

The writer just nodded his head and started the coffee machine, avoiding looking at them.

Kate turned around, took a cup from the counter and handed it to her partner. "Here, I made this for you." She said with a smile.

The writer stood there for a few seconds, looking at the steaming cup of coffee his partner was handing him, as if it were some kind of weird artifact.

"Castle?"

He snapped out of his trance and took the cup, leaning in to put a quick peck on Beckett's cheek. With that, he took a sip of his coffee and walked out of the break room with a smug smile on his face.

"That was weird." Will said; his brows furrowed over his blue eyes. "I still don't know how you've put up with him for all this time…"

Kate's still startled eyes turned to glare at Will, who was shaking his head, looking at the door Castle had walked out through. "I don't 'put up' with him, Will. He's my partner."

The agent laughed. "Still. He's nothing but trouble, Kate. He's a joke."

"Hm." Kate chugged, following Castle's steps to the bullpen. "You have no idea the number of times that _joke_ has saved my life." She said, stopping under the threshold to look Sorenson in the eyes. "He can be a little… singular, but he's the best partner I could ever ask for."

* * *

It was their second day working with the FBI and they were reaching nothing but dead ends. The time for little Jeremy Keller would be coming to an end if they didn't find anything soon.

Beckett was so frustrated that it was literally dangerous being around her. She hated these kinds of cases. Knowing that someone's life was on the line, and that it was her responsibility to keep that person alive, made her overly irascible and jumpy.

Castle was very aware of this fact, after all, he knew perfectly well his partner of almost four years. So, he tried to stay away from her the best he could, only interrupting her to hand her a new cup of coffee every few hours. She always gave him a nod and a subtle smile, going back to work the moment she took the first sip.

Sorenson had been watching the exchange between the partners all day, finding incredibly funny that she couldn't stand Castle around her. Maybe he was not such a good partner after all.

The agent walked to Beckett's desk with a cocky smile on his face, placing his arms at both sides of Beckett's, leaning closer to talk to her.

"Hey. You look tired. Wanna go get something to eat?" He asked, his eyes on Castle, who was staring at them waiting for Beckett to vent out any second.

The detective took a deep breath and tried to school her features and her bad temper. Will didn't know her that well anymore, and he was in charge of the investigation. She just couldn't yell at him out of the blue.

"I… I'm not hungry, Will." She replied, her voice a little shaky due to the effort it was taking for her not to snap at him.

"Come on, Kate. It's almost 2 pm and you haven't eaten anything since that pastry Writer-Monkey fed you this morning."

Kate turned her chair so they were face to face. "I'd really appreciate it if you called him by his name." She said, her eyes piercing Sorenson's.

The agent nodded and smiled wickedly. "Ok. Sorry." He said. "Come on, let's go get something to eat."

"I don't know if you remember there's a missing kid we need to find. It's been over 60 hours already, Will. We don't have much time left." She said, spinning her chair again so that she could go back to work.

Castle was observing their exchange from a safe distance, enjoying every time Kate turned down Sorenson's invitation.

The agent kept looking at Rick when he talked to Beckett, as if trying to follow his every reaction to his actions towards the detective, and Castle found that very amusing. Was it some kind of game for him? The jerk…

Castle heard the ding of the elevator and saw the delivery guy walking into the bullpen carrying enough food to feed an army. The writer approached the man, paid him, and took the bags to the conference room, setting everything on the table.

When he was done, he went back out and caught everyone's attention with a loud whistle.

"Ok, everyone! Lunch's ready. Be careful not to overdo it, we've got a lot of people here. Bon Appetite!"

The bullpen burst into a loud fuss then, with people leaving their desks and mouthing their excitement about the food, and thanking Castle when they walked inside the conference room.

Kate raised her head from her desk and turned to smile mischievously at Will. "See? _Writer-Monkey_ takes care of everything."

* * *

It had been close. He could be dead by now if it weren't for Sorenson.

They found a lead that took them to a warehouse near the river. Beckett had asked him to stay in the car at least 20 times before she left to get inside with her team. He had agreed. He had promised to stay put and don't leave the car under no circumstances, but when he saw the man running out of the building, dragging the kid with him, he just couldn't do nothing.

He got out of the car right when the guy was passing by it, yanked on the kid's arm and threw him into the car backseat, with such bad luck that he fell to the floor and found himself with a gun pointed to his head.

Ryan and Esposito, who were at the tail of the group, heard the kid's screams and called Beckett; they were surrounding the car in a matter of seconds.

"Drop it, Moss!" Beckett called from behind the man.

The guy laughed and shook his head. "No way, pretty face. If I'm going down, he sure as hell is coming with me." He yelled.

"He has nothing to do with this. It's not his fault that you were fired." Kate tried to reason. "Castle, you ok?"

The writer nodded the best he could from lying on the ground; his voice was nowhere to be found.

Sorenson moved from beside Beckett very slowly, until he was facing the man, his gun pointed to his head.

"Drop The Gun." He said, taking a step closer to Moss.

The man shook his head and removed the gun safety. "Don't get any closer or your friend dies."

Castle could hear the hitch on Beckett's breathing. She made a sign to Will, begging him to be careful.

"No one needs to die, Carl. We can end this nice and easy. Just drop your gun."

Moss cocked the gun and put his finger on the trigger. "I won't surrender."

The agent made a sign to one of his men and shot twice. Moss fell to the floor, right were Castle had been lying seconds before, when one of Sorenson's men rolled him out of there.

The aftermath was crazy. Ambulances and FBI SUVs crowded the place, and what had looked like and abandoned compound minutes before, now had the transit of Times Square at rush hour.

Castle was sitting in the back of an ambulance, a paramedic cleaning a tiny cut on his eyebrow, when he saw Beckett coming.

The detective gave him a killer glare and stopped right beside the ambulance door.

"Is he ok?" She asked the woman cleaning his face.

"Yes. It's just a small cut. Everything else is just fine. He's good to go." She said, walking out of the van to give them some privacy.

Kate moved closer to him and threw a hard punch to his shoulder.

"OWWWW!" Castle yelled. "What was that for?"

Kate glared at him again. "What was that for? You could be dead, you idiot! You scare me like that again and I'll be the one pointing the gun at you."

Not giving him time to reply or even apologize, she left to check on the little boy.

Ryan and Esposito escorted him to their car and helped him inside. He only had that little cut on the eyebrow, but the rest of his body was sore from his fall and lying on the floor. Everything hurt like hell.

The craziness went on for a while. They had to call the kid's parents and wait for the ME and the CSU units to arrive before they could go back to the precinct, but the worst part of it all was that he had to watch how she did all of that with Sorenson, while he had to stay in the car.

The agent hadn't left her side since the shooting. He knew she was shaken and he wanted to be there by her side, playing the great, brave hero who had saved her partner from a certain death.

Right when they were about to leave the place, he saw how Sorenson grabbed her arm before she could get in the car and said something to her. She just nodded and walked into his open arms, letting him hug her. She let him hug her!

* * *

Back at the precinct, after being reprimanded by Gates for putting the team in danger and embarrass the whole NYPD, he headed to the break room to talk to Beckett. He knew she was mad at him and he had wanted to apologize since she had approached him at the ambulance.

When he walked inside the room Sorenson was sitting at the table and Kate was leaning against the counter, her gaze lost into space. They were both quiet, probably going through the previous events.

"Hey." He said, reaching for the coffee machine. "I… I wanted to apologize for what happened before. I'm sorry I put all of you in danger."

Sorenson looked up at him and nodded. "It's ok, Castle. Everything ended up fine. You should be careful, though. That guy could have killed you. Maybe next time you won't be that lucky."

Kate moved from where she was and sat on the couch, leaving Castle alone in the other side of the room. "There won't be a next time."

Both men turned to look at her surprised.

"WHAT?" Castle asked. "What do you mean, 'there won't be a next time'?"

Her green eyes rose, meeting his blue ones for the first time in hours. "You really can't think I'm going to let you do something like that again, Castle. It was too close this time."

"Come on, Beckett! Nothing happened. I saved the kid! Doesn't that count at all?" He said, his jaw tense, trying to control himself in front of Sorenson.

"Oh, yeah, sure. You saved the kid…" She snorted. "That guy could have killed you both thanks to your stupidity. You're not a cop, Castle. You're just an idiot who likes to play hero, but you're done with it."

"I'm not done with anything. You can't decide what I can or can't do, Beckett." He yelled, totally pissed at her. "None of you have stopped to think about what could have happened if I hadn't done what I did. That boy would be dead by now and you know it!"

Kate stood up from the couch and walked to be face to face with him. "Yes. You're right. Or maybe it could have been you bleeding to death on that floor."

They were both breathing heavily, their eyes locked and their hands in fists. The tension was so thick you could cut it with a knife.

Sorenson cleared his throat. "Ok, let's calm down. It was a dumb idea, Castle, but you saved the kid. That's all that matters. And Kate? You need to relax. You guys can talk about this tomorrow, when everything's cooled down a bit."

Right that moment Ryan and Esposito stepped inside the break room, talking about going to have a drink at the Old Haunt to celebrate closing the case. None of them was in the mood for it, but their teammates insisted until they both said yes.

* * *

At the bar, Beckett tried to avoid Castle as much as she could. She was mad at him, mostly because he had scared the shit out of her and she was having trouble dealing with it. It had been so close…

The writer was sitting at the bar with Espo and Ryan, the three of them laughing at some stupid joke. He couldn't help roaming the room every now and then looking for her. Even though they were mad at each other, he needed to know where she was, if she was having fun, or being miserable because of him.

He spotted her sitting in a booth with a couple of FBI agents. A minute later, Sorenson sat beside her, handing her a beer with a big smile on his stupid face. The other agents left the booth, leaving them alone.

Castle didn't like that. He needed to talk to Kate. Now. Apologize, beg for her forgiveness; whatever it took to keep her far from Mr. FBI. He would fall to his knees if it were necessary.

It took him a few minutes coming up with a good excuse to leave the bar without Ryan and Espo suspecting anything. He didn't want to have them mocking him about this for the rest of his life.

When he reached the booth, he was greeted by something he was not expecting at all.

Sorenson had been trying to make Kate accept going out with him on her day off. He said he wanted to catch up and talk about the old times. She was tempted. She really liked Will. He was one of those men you know are not good for you, but still want to have close; maybe hoping for them to change and become exactly what you need. She knew how those things ended, so she kept saying no every time he asked.

After a couple of beers, he asked again. "Come on, Kate, have dinner with me!"

"Will, you can ask all you want, but the answer is always going to be the same. No." She said, taking a sip f her beer. "We both know what you're looking for, and it's not going to happen."

"We're good together. You know that. Why deny us that?"

She shook her head and put the bottle down. "We _were_ good together for a while. Now? Not that much."

The agent moved closer to her, stroking her cheek with his hand. "You don't know that." He said, leaning closer and catching her lips with his.

He caught her totally by surprise, and it took her a while to move away from him, finding Castle in front of her, his eyes and mouth wide open.

"Castle! Uh, hi!"

The writer blinked hard, trying to block the image that was already haunting him. "Hi. I was... I just wanted to talk to you, but I guess you're busy... Um…yeah. Uh... I'll leave you two alone." He said, turning around to leave.

Kate stared at him for a second, still a little startled. "No! Wait, I... I was leaving. Take me home? Please?"

She bit her lip in that way he loved so much, looking incredibly guilty while she untangled herself from Will's arms.

Castle nodded, turning around to leave again.

Kate stood up, giving Sorenson an apologetic look. "I'm sorry Will, I..."

The agent smiled. "It's ok. I should have known..." He said, giving her hand a quick squeeze. "Bye Kate."

"Bye."

The detective smiled back at him before walking away to meet Castle at the door.

* * *

He was waiting her outside. His eyes were closed and his hands were hidden inside his pockets. She knew he was hurt, maybe even mad at her. She needed to fix it.

Kate walked closer to him, leaning on the railing right by his side, shoulders almost touching.

"Hey. Sorry about that." She said, nodding towards the door.

Castle sighed, opening his eyes to look at her. "No. I'm sorry. I never meant to interrupt."

She couldn't help it and she laughed. "You didn't interrupt anything, Castle."

"Well, it sure looked like something to me..." He replied all hurt.

Kate sighed and shook her head. Castle started to walk away from her, but she stopped him by grabbing his hand.

"Do you ever listen when I speak, Castle?"

"What?"

She squeezed his hand and brought it up to her chest. "Didn't I make myself clear when I told you a long time ago that I'm a one writer girl?"

Castle swallowed hard, looking at her completely stunned. "Well, he's not a writer..."

She walked closer to him, tilting forwards enough for her nose to brush his ear. "Hm, ok. Let me rephrase that for you: I. Am. A. One. _Rick Castle_. Girl." She whispered, biting his earlobe afterwards and feeling him shiver.

He looked at her then, his eyes watery. He was surprised, amazed, but over all, he was happy.

"Take me home, writer boy, before I change my mind."

THE END.

* * *

**I hope you guys liked this one ;) Feel free to submit you ideas for upcoming chapters!**

**Thanks for reading :)**


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